Light source device for image display device

ABSTRACT

A highly precise and durable light source device  50  for a three-dimensional display does not use a mechanical construction and thus can rapidly move an illuminating point on a light source to a position that best matches the positional movement of an observer. The light source device has an image display means  52  that creates an image using transmitted light. The LED arrays  51 U,  51 D of white LEDs  1  are arranged in two tiers and display a right-eye image and a left-eye image, respectively. The light source device also has an LED control means  53  that performs a turn-on control on the white LEDs  1  in the LED arrays  51 U,  51 D.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light source device forthree-dimensional display which rapidly turns on a small number of LEDsto present a stereoscopic image to an observer in a wide range ofviewing angle even if the observer moves sideways or the image is viewedby two or more observers from multiple visual points. More particularly,the invention relates to a light source device for three-dimensionaldisplay that has an image display means for creating an image usingtransmitted light.

2. Description of the Prior Art

A technology for visualizing an object in three dimensions has beenunder development and studies on a method of displaying athree-dimensional image has been conducted in many fields, with avariety of techniques already put to practical use. There are two typesof three-dimensional visualization system. One type requires an observerto wear a device such as special eyeglasses or goggles and the otheruses no special device on the observer.

The first system (eyeglass type) includes a so-called anaglyph system,in which a viewer wears a pair of eyeglasses, one attached with a redfilter and the other with a blue filter; and a polarized eyeglasssystem, which uses a pair of eyeglasses attached with polarizing filtersthat transmit linearly polarized light and whose transmission axes areset perpendicular to etch other. In these systems a viewer sees with histwo eyes disparate images of an object that produce the binocularparallax so that the viewer can see a generally stereoscopic view.However, with these systems the viewer needs to wear cumbersome specialeyeglasses.

Among proposed stereoscopic display systems that do not use the specialeyeglasses are a parallax barrier system and a lenticular system.

Japanese Patent Disclosure No. 10-63199 discloses a stereoscopic imagingsystem in which, as shown in FIG. 5, a right-eye polarizing filterportion 66 a and a left-eye polarizing filter portion 66 b with theirpolarizing axes set perpendicular to each other are arranged on theleft- and right-side areas of a light emitting surface of atwo-dimensional or planar light source 65; in which rays of light thathave passed through the filter portions 66 a, 66 b are collimated by aFresnel lens 63 into parallel rays that are then projected onto a liquidcrystal device 62; and in which the liquid crystal device 62 has on bothsurfaces thereof linear polarizing filters 621, 622 each comprisinghorizontal lines of filters La, Lb hang their polarizing axes setperpendicular to each other, with the horizontal filter lines La, Lbalternated in the vertical direction. In this example, the opposinglinear polarizing filter lines, one on the light source 65 side and theother on the viewer side, are set such that their polarizing axes areperpendicular to each other. A liquid crystal panel 620 of the liquidcrystal device 62 has an image formed thereon so that image informationfor the right eye and image information for the left eye are arrangedalong the horizontal filter lines of the two opposite polarizing filtersand alternated in the vertical direction, permitting either of the imageinformation to appear every other horizontal line.

In any of the systems described above—the binocular parallax barriersystem, the lenticular system and the system disclosed in JapanesePatent Disclosure No. 10-63199—since the stereoscopic viewing range islimited, if the observer's position is shifted left or right evenslightly, the stereoscopic image is inverted left or right or only aplanar image is displayed. Another problem with these systems is that animage can only be presented to a single observer. To deal with theseproblems, a method has been proposed which involves measuring theposition of an observer and mechanically moving the light source (asindicated by an arrow A in FIG. 5) according to the observer's movement.This method, however, is not practical because of its slow responsespeed and because a mechanically driving device easily wears out andlacks a sufficient durability. Further, when an observer shiftssideways, he or she cannot see the intended stereoscopic image.

Further, in a case where a stereoscopic image source is received, evenif the same planar images for the left and right eyes are displayed atthe same time, the two planar images reaching the left and right eyeshave half an original resolution of the liquid crystal device becausethe left and right eyes receive the left- and right-eye planar imagesseparately.

The present invention has been accomplished to overcome these problems.A first object of the present invention is to provide a highly preciseand durable light source device for three-dimensional display which doesnot use a mechanical construction and thus can rapidly move anilluminating point on a light source to a position that best matches thepositional movement of an observer. In this invention, a control to movethe position of an illuminating point on a light source is referred toas a turn-on control.

A second object of this invention is to provide a light source devicefor three-dimensional display which can turn a light source on and offat a speed high enough to allow the light source to be turned off duringsynchronization signal and blanking periods to eliminate unwantedafterimages and interferences and reduce power consumptionssignificantly. In this invention, a control for turning off the lightsource during the synchronization signal and blanking periods isreferred to as a turn-off control.

A third object of this invention is to provide a light source device forthree-dimensional display which, when used on a time-division typethree-dimensional display, can obviate the use of a shutter device in alight source thus simplifying the construction and eliminating a lighttransmission loss.

A fourth object of this invention is to provide a light source devicefor three-dimensional display which, with a limited number of LEDs as alight source, can form a wide viewing angle image on a two- orthree-dimensional display. In this case, by using a known eye positiontracking device, such as an ultrasonic tracking device, infraredtracking device or image tracking device, it is possible to present astereoscopic image to an observer even if eyes of the observer move orthe display is viewed by two or more observers.

A fifth object of this invention is to provide a light source device forthree-dimensional display which can easily display a stereoscopic imagesource as a planar or two-dimensional image. That is, even if the sameplanar images for the left and right eyes (par image source) arepresented to both eyes, the image cannot be seen at an increasedresolution because the left and right eyes receive the left- andright-eye images separately. It is therefore desired that thethree-dimensional display can also display a planar image.

SUMMARY OF THE INVENTION

The present invention solves the above-mentioned problems with thefollowing means.

A first aspect of the present invention provides a light source devicefor three-dimensional display having an image display means, wherein theimage display means forms an image using transmitted light, the lightsource device comprising: an LED array having white LEDs or RGB LEDsarranged in two horizontal rows one above the other, and an LED controlmeans for performing an on-off control on the horizontal rows of thewhite LEDs or RGB LEDs in the LED array.

With this invention, since the light source uses white LEDs or RGB LEDsthat have a small power consumption and a fast on-off switching speed,the control of the LED control means makes it possible to turn on or offany of the LEDs of the light source and reduce the power consumption.

A second aspect of the present invention provides a light source devicefor three-dimensional display according to the first aspect, wherein thedisplay is a three-dimensional display to present different images toright and left eyes of an observer and the upper and lower LED arraysconstitute a light source portion for presenting an image for the righteye and a light source portion for presenting an image for the left eye,respectively.

With this invention, a stereoscopic image visualization control with ahigh degree of freedom can be realized by controlling the turn-on of theright- and left-eye image light source portions in the LED array by theLED control means.

A third aspect of the present invention provides a light source devicefor three-dimensional display according to the second aspect, whereinthe display has a position identifying means which measures a positionof an observer relative to the display and outputs a correspondingposition signal, and the LED control means performs a turn-on control onthe white LEDs or RGB LEDs based on the position information so as tokeep an image viewable by the observer.

With this invention, illuminating points in the right- and left-eyeimage light source portions can be moved, according to the observerposition information, at high speed to positions that match the positionof an observer. During this process no mechanical actions are performed,assuring high precision and high durability.

A fourth aspect of the present invention provides a light source devicefor three-dimensional display according to the second aspect, whereinthe display has a controller operated by the observer, and the LEDcontrol means performs a turn-on control on the white LEDs or RGB LEDsbased on operation information from the controller 80 as to change animage viewed by the observer.

With this invention, illuminating points in the right- and left-eyeimage light source portions can be moved at high speed to any desiredpositions by the observer operating the controller. During this processno mechanical actions are performed, assuring high precision and highdurability.

A fifth aspect of the present invention provides a light source devicefor three-dimensional display according to the second aspect, whereinthe display has a position identifying means which counts the number ofobservers, measures positions of the observers relative to the displayand outputs corresponding position signals, and the LED control meansperforms a turn-on control on the white LEDs or RGB LEDs based on theposition information so as to keep images viewable by the observers.

With this invention, appropriate stereoscopic images can be presented toa plurality of viewers located at different positions.

A sixth aspect of the present invention provides a light source devicefor three-dimensional display according to the second aspect, whereinthe right-eye image light source portion and the left-eye image lightsource portion of the LED array are on-off controlled.

In a three-dimensional display that displays right- and left-eye imagesin a time-division manner, this invention can obviate the use of ashutter device in a light source thus simplifying the construction andeliminating a light transmission loss.

A seventh aspect of the present invention provides a light source devicefor three-dimensional display according to the second aspect, whereinthe LED control means changes an interval between lighted parts of theright-eye image light source portion and the left-eye image light sourceportion of the LED array according to a distance of an observer from thedisplay.

With this invention, an appropriate stereoscopic image can be presentedto an observer wherever the observer is located by changing the intervalbetween the lighted parts of the right- and left-eye image light sourceportions according to the position of the observer.

An eighth aspect of the present invention provides a light source devicefor three-dimensional display according to the first aspect, wherein thetwo horizontal rows, one above the other, of the white LEDs or RGB LEDsin the LED array are arranged such that the LEDs in one of the rows areplaced side by side with or staggered from those in the other row, andthe LED control means performs the on-off control on the LED horizontalrows in the LED array.

With this invention, the right- and left-eye LEDs at the central portionof the LED array can easily be separated from each other, reducinginterferences and crosstalks between the right-eye image and theleft-eye image which adversely affect a stereoscopic image formed. Thecrosstalk reduction is realized because light interferences between theright- and left-eye illuminating LEDs are prevented by their verticalseparation, i.e., the right- and left-eye illuminating LEDs are arrangedin the upper and lower rows in the LED array, respectively. In thiscase, if a partition wall or the like is arranged between the upper andlower rows of LEDs, the crosstalks can better be prevented. When the tworows of LEDs are turned on simultaneously, the light quantity doubles,forming a brighter image. Further, the simultaneous lighting of the twoLED rows can display a plantar image from a stereoscopic image signal.

That is, when a planar image signal is received, it is transferred inthe same signal transmission mode as used in transferring a stereoscopicimage signal. This enables a high resolution planar image to bedisplayed by only performing simple turn-on processing on the LED arrayon the receiving side.

According to a ninth aspect of the present invention, the LED controlmeans turns on and off appropriate white LEDs in the LED array and scansthe illuminating LEDs across the LED array at high speed in a horizontaldirection. When applied to a two-dimensional display, this invention canform a wide viewing angle image with a limited number of LEDs as a lightsource.

According to a tenth aspect of the present invention, the light sourcedevice for three-dimensional display can be used on three- ortwo-dimensional displays of television sets, game machines, personalcomputers, cell phones or mobile terminals.

This invention enables a stereoscopic image to be formed not only onlarge screens of television sets, game machines and personal computersbut also on small screens of cell phones and mobile terminals which caneasily move relative to sight lines of observers. This invention alsoallows these screens to be used as two-dimensional displays that requirea wide viewing angle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a display that uses a light source device forthree-dimensional display according to a first embodiment of theinvention.

FIG. 2 illustrates a display that uses a light source device forthree-dimensional display according to a first embodiment of theinvention.

FIG. 3 illustrates a display that uses a light source device forthree-dimensional display according to a first embodiment of theinvention.

FIG. 4 illustrates a display that uses a light source device forthree-dimensional display according to a second embodiment of theinvention.

FIG. 5 illustrates an example of a conventional three-dimensionaldisplay.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Now, embodiments of the present invention will be described by referringto the accompanying drawings.

FIG. 1 to FIG. 4 show embodiments of this invention, FIG. 1 to FIG. 3representing a first embodiment of the invention and FIG. 4 a secondembodiment.

In the following description it is assumed that a display used is athree-dimensional display. In the embodiments that follow, an imagedisplay means may use basically the same construction as the displaydisclosed in Japanese Patent Disclosure No. 10-63199. In that case, asshown in FIG. 5, the image display means has a right-eye polarizingfilter portion 66 a and a left-eye polarizing filter portion 66 b. Raysof light that have passed through the filter portions 66 a, 66 b arecollimated by the Fresnel lens 63 into parallel rays that are thenprojected onto the liquid crystal device 62.

First Embodiment

In this embodiment, as shown in FIG. 1 and FIG. 2, a light source device50 for three-dimensional display has an LED array 51 constructed of twotiers, an upper tier 51U and a lower tier 51D. Disposed in front ofwhite LEDs 1 of the LED array 51 is a polarizing filter 54 which hasright- and left-eye polarizing filters 54U, 54D corresponding to theupper tier 51U and lower tier 51D of the LED array 51. The polarizingfilters 54U, 54D transmit light from the upper tier 51U and the lowertier 51D of the LED array 51, respectively, and have their polarizationaxes set perpendicular to each other.

An LED control means 53 performs an on-off control on each LED array51U, 51D.

First, let us explain about a case where there is only one observer 70.

A position of the observer 70 is checked by a position identifyingmeans, and an illuminating region 73 of the upper and lower LED arrays51U, 51D is turned on to present a stereoscopic image to the observer70. At this time, the illuminating region is moved according to theposition of the observer 70 detected by the position identifying means55 to present a stereoscopic image to the observer. When the observer islocated at the center of the LED array 51, it is of course not necessaryto provide the position identifying means 55.

Next, a case of two observers 70, 71 will be explained. In this case, asshown in FIG. 1 and FIG. 2, the LED control means 53 receives signalsfrom the position identifying means 55, sets two illuminating regions73, 74 on the two LED arrays 51U, 51D, and performs a turn-on control onthese illuminating regions alternately at high speed. During thisprocess, other LEDs 1 than those of the illuminating regions 73, 74 arenot lighted and, at any given instant, only one of the illuminatingregions 73, 74 illuminates. As shown in FIG. 1, the light source device50 includes an LED array 51 having a plurality of white LEDs 1 arrangedin a plurality of horizontal, parallel rows, an image display means 52and a Fresnel lens acting as a convex lens. The image display means 52may use a transmission type liquid crystal panel.

The LED array 51 is turned on and off by the LED control means 53. InFIG. 1 reference number 55 represents apposition identifying means thatmeasures the positions of the observers 70, 71. The position identifyingmeans 55 uses a known position detection means of infrared or ultrasonictype to locate the positions of the observers 70, 71 and sendsinformation on the observers' position to the LED control means 53.

In this embodiment, the LED control means 53 quickly turns on and scansilluminating regions of the white LEDs 1 in the LED array 51 to the leftand right. In FIG. 1, lit LEDs are represented by black dots “•” andunlit LEDs by blank dots “∘” (this representation also applies in thefollowing description).

By performing the turn-off control that turns off the white LEDs 1during the synchronization signal and blanking periods of the imagedisplay means 52, not only can unwanted afterimages and interferences beeliminated but the power consumption can also be reduced. Further, in athree-dimensional display the light source device using a small numberof LEDs as a light source in combination with the Fresnel lens canproduce an image with a wide viewing angle.

In this embodiment, since the right-eye LED array and the left-eye LEDarray are separated vertically, the distance between the illuminatedregions for the right and left eyes increases, reducing interferencesbetween rays of light from these illuminated regions, which in turnreduces crosstalks between right- and left-eye images that have adverseeffects on a stereoscopic image produced.

Further, as shown in FIG. 2, if in addition to regions 62, 63 in the twoLED arrays 51U, 51D for the right and left eyes, LEDs in regions 64, 65located above and below the regions 62, 63 are also illuminated at thesame time, images supplied as a three-dimensional image to the imagedisplay means are both displayed as two-dimensional or planar images tothe observer 70. In this case, since a light quantity doubles, abrighter image can be displayed. A switchover between a stereoscopicimage and a planar image can easily be done by an electric control andrequires no mechanical control. This means no mechanical wear occurs.

Second Embodiment

In this embodiment, as shown in FIG. 4, a light source device 50 forthree-dimensional display has an LED array 51 constructed of two tiers,an upper tier 51U and a lower tier 51D, with white LEDs 1 of these tiersstaggered in a horizontal position.

In this embodiment, the right- and left-eye LEDs at the central portionof the LED array can easily be separated from each other, reducinginterferences. That is, this embodiment can reduce crosstalks betweenthe left- and right-eye images and therefore adverse effects on astereoscopic image formed.

The use of the three-dimensional display of this invention may forexample include, but is not limited to, display portions of televisionsets, game machines, personal computers, cell phones and mobileterminals.

Although the LED array 51 in this embodiment is made up of white LEDs,each of the LEDs in the LED array may be formed by combining threeprimary color LEDs, or RGB LEDs, so that the RGB LEDs as a whole producewhite light.

Further, it should be noted that the light source device forthree-dimensional display according to this invention is not limited inconstruction to the embodiments described above and that a variety ofmodifications may be made without departing from the spirit of theinvention.

INDUSTRIAL APPLICABILITY

As described above, the light source device for three-dimensionaldisplay according to the present invention offers the followingadvantages.

According to a first aspect of this invention, since two horizontal rowsof LEDs, upper and lower LED arrays, with a small power consumption anda fast on-off switching speed are used as a light source to display aright-eye image and a left-eye image, respectively, any desired point onthe light source can be turned on or off by controlling the LED controlmeans and the power consumption of the light source device reduced.

According to a second aspect of this invention, a stereoscopic imagevisualization control with a high degree of freedom can be realized bycontrolling the turn-on of the right- and left-eye image light sourceportions in the LED array by the LED control means.

According to a third aspect of this invention, illuminating points inthe right- and left-eye image light source portions can be involved,according to observer position information, at high speed to positionsthat match the position of an observer. Since during this process nomechanical actions are performed, the control can be made with highaccuracy and high durability.

According to a fourth aspect of this invention, illuminating points inthe right- and left-eye image light source portions can be moved at highspeed to any desired positions by the observer operating the controller.Since during this process no mechanical actions are performed, thecontrol can be made with high accuracy and high durability. Even if anobserver position shifts sideways, he or she can reliably see astereoscopic image.

According to a fifth aspect of this invention, since the display has aposition identifying means which counts the number of observers,measures positions of the observers relative to the display and outputscorresponding position signals and since the LED control means performsan on-off control on the white LEDs based on the position information soas to keep images viewable by the observers, appropriate stereoscopicimages can be presented to a plurality of viewers located at differentpositions.

According to a sixth aspect of this invention, since the right- andleft-eye image light source portions of the LED array are on-offcontrolled, a shutter device in a light source can be obviated in athree-dimensional display that displays right- and left-eye images in atime-division manner. This in turn simplifies the construction andeliminates a light transmission loss.

According to a seventh aspect of this invention, since the LED controlmeans changes an interval between lighted parts of the right- andleft-eye image light source portions of the LED array according to adistance of an observer from the display, an appropriate stereoscopicimage can be presented to the observer wherever the observer is locatedby changing the interval between the lighted parts of the right- andleft-eye image light source portions according to the position of theobserver.

According to an eighth aspect of this invention, since the twohorizontal rows, one above the other, of the white LEDs or RGB LEDs inthe LED array are arranged such that the LEDs in one of the rows arestaggered from or placed side by side with those in the other row, andthe LED control means performs the on-off control on the LED horizontaltows in the LED array, the right- and left-eye LEDs at the centralportion of the LED array can easily be separated from each other,reducing interferences and crosstalks between the right-eye image andthe left-eye image which adversely affect a stereoscopic image formed.The crosstalk reduction is realized because light interferences betweenthe right- and left-eye illuminating LEDs are prevented by theirvertical separation, i.e., the right- and left-eye illuminating LEDs arearranged in the upper and lower rows in the LED array, respectively. Inthis case, if a partition wall or the like is arranged between the upperand lower rows of LEDs, the crosstalks can better be prevented. When thetwo rows of LEDs are turned on simultaneously, the light quantitydoubles, forming a brighter image. Further, the simultaneous lighting ofthe two LED tows can display a planar image from a stereoscopic imagesignal.

According to a ninth aspect of this invention, since the LED controlmeans turns on and off appropriate white LEDs in the LED array and scansthe illuminating LEDs across the LED array at high speed in a horizontaldirection, a wide viewing angle image can be created with a limitednumber of LEDs as a light source in a two-dimensional display.

According to a tenth aspect of this invention, a stereoscopic image canbe formed not only on large screens of television sets, game machinesand personal computers but also on small screens of cell phones andmobile terminals which can easily move relative to sight lines ofobservers. These screens can also display two-dimensional images thatrequire a wide viewing angle.

1. A light source device for three-dimensional display having an imagedisplay means, wherein the image display means forms an image usingtransmitted light, the light source device comprising: a LED arrayhaving white LEDs or RGB LEDs arranged in two horizontal rows one abovethe other; and a LED control means for performing an on-off control onthe horizontal rows of the white LEDs or RGB LEDs in the LED array.
 2. Alight source device for three-dimensional display according to claim 1,wherein the display is a three-dimensional display to present differentimages to right and left eyes of an observer and the upper and lower LEDarrays constitute a light source portion for presenting an image for theright eye and a light source portion for presenting an image for theleft eye, respectively.
 3. A light source device for three-dimensionaldisplay according to claim 2, wherein the three-dimensional display hasa position identifying means which measures a position of an observerrelative to the three-dimensional display and outputs a correspondingposition signal, and the LED control means performs a turn-on control onthe white LEDs or RGB LEDs based on the position information so as tokeep an image viewable by the observer.
 4. A light source device forthree-dimensional display according to claim 2, wherein thethree-dimensional display has a controller operated by the observer, andthe LED control means performs an on-off control on the white LEDs orRGB LEDs based on operation information from the controller so as tochange an image viewed by the observer.
 5. A light source device forthree-dimensional display according to claim 2, wherein thethree-dimensional display has a position identifying means which countsthe number of observers, measures positions of the observers relative tothe display and outputs corresponding position signals, and the LEDcontrol means performs an on-off control on the white LEDs or RGB LEDsbased on the position information so as to keep images viewable by theobservers.
 6. A light source device for three-dimensional displayaccording to claim 1, wherein the LED control means performs a turn-oncontrol on the right-eye image light source portion and the left-eyeimage light source portion of the LED array.
 7. A light source devicefor three-dimensional display according to claim 2, wherein the LEDcontrol means changes an interval between lighted parts of the right-eyeimage light source portion and the left-eye image light source portionof the LED array according to a distance of an observer from thedisplay.
 8. A light source device for three-dimensional displayaccording to claim 1, wherein the two horizontal rows, one above theother, of the white LEDs or RGB LEDs in the LED array is arranged suchthat the white LEDs or RGB LEDs in one of the rows are placed side byside with or alternated to those in the other row, and the LED controlmeans performs the turn-on control on the horizontal rows of the whiteLEDs or RGB LEDs in the LED array.
 9. A light source device forthree-dimensional display according to claim 1, wherein the LED controlmeans turns on appropriate white LEDs in the LED array and scans theilluminating LEDs across the LED array at high speed in a horizontaldirection.
 10. A light source device for three-dimensional displayaccording to claim 1, which is used on three- or two-dimensionaldisplays of television sets, game machines, personal computers, cellphones or mobile terminals.